Patient Self Determination Act of 1990 - Amends titles XVIII (Medicare) and XIX (Medicaid) of the Social Security Act to require hospitals, skilled nursing facilities, home health agencies, hospice programs, and health maintenance organizations to: (1) inform patients of their rights under State law to make decisions concerning their medical care; (2) periodically inquire as to whether a patient executed an advanced directive and document the patient's wishes regarding their medical care; (3) not discriminate against persons who have executed an advance directive; (4) ensure that legally valid advance directives and documented medical care wishes are implemented to the extent permitted by State law; and (5) provide educational programs for staff, patients, and the community on ethical issues concerning patient self-determination and advance directives.

Directs the Secretary of Health and Human Services to: (1) arrange with the Institute of Medicine of the National Academy of Sciences for a study assessing the implementation of directed health care decisions; and (2) develop and implement a demonstration project in selected States to inform the public of the option to execute advance directives and a patient's right to participate in and direct health care decisions.